[X-plor] CNS ERROR: "Error: required observed amplitude array "fobs" does not exist"

[pradeeppallan from gmail.com]

Hi,

I am trying to run 'translation.inp', part of molecular replacement
for a DNA using
CNS version 1.1 on a SGI machine. cross_rotation.inp job runs and
gives the output.
However, translation.inp gives the error message (please scroll down):

          ============================================================
          |                                                          |
          |            Crystallography & NMR System (CNS)            |
          |                         CNSsolve                         |
          |                                                          |
          ============================================================
           Version: 1.1
           Status: General release
          ============================================================
           Written by: A.T.Brunger, P.D.Adams, G.M.Clore, W.L.DeLano,
                       P.Gros, R.W.Grosse-Kunstleve, J.-S.Jiang,
                       J.Kuszewski, M.Nilges, N.S.Pannu, R.J.Read,
                       L.M.Rice, T.Simonson, G.L.Warren.
           Copyright (c) 1997-2001 Yale University
          ============================================================
           Running on machine: test1 (SGI/IRIX,64-bit)
           Program started by: pradeep
           Program started at: 18:06:35 on 22-Jan-08
          ============================================================

 FFT3C: Using complib.sgimath
.
.
.
.
.
.
CNSsolve> if ( &BLANK%anom_library = false ) then
 NEXTCD: condition evaluated as false
 CNSsolve>   @@&anom_library
 CNSsolve> else
 CNSsolve>   set echo=off end
 ANOMalous=FALSe {OFF}
 NEXTCD: condition evaluated as false
 CNSsolve> end if
 CNSsolve>
 CNSsolve> xray
 XRAY>
 XRAY>   set echo=off end
 NEXTCD: condition evaluated as false
 Reciprocal space object FOBS does not exist.
 NEXTCD: condition evaluated as true
**************************************************************
 Error: required observed amplitude array "fobs" does not exist
 **************************************************************

 %  error encountered: ABORT statement specified.
   (CNS is in mode: SET ABORT=NORMal END)
 *****************************************************
 ABORT mode will terminate program execution.
 *****************************************************
 Program will stop immediately.
          ============================================================
           Maximum dynamic memory allocation:     1724448 bytes
           Maximum dynamic memory overhead:           352 bytes
           Program started at: 15:30:08 on 22-Jan-2008
           Program stopped at: 15:30:09 on 22-Jan-2008
           CPU time used:       0.0990 seconds
          ============================================================

I tried running the steps (cross_rotation and translation) with a
known data set, and it gives
the same error. [The molecular replacement solution was obtained
originally in CNS (version 1.0),
that have been refined to 1.1A].

The header of the hkl file reads:
NREFlections= 18313
ANOMalous= FALSe
DECLare NAME=IOBS  DOMAin=RECIprocal TYPE=REAL END
DECLare NAME=SIGI  DOMAin=RECIprocal TYPE=REAL END
DECLare NAME=FOBS  DOMAin=RECIprocal TYPE=REAL END
DECLare NAME=SIGMA DOMAin=RECIprocal TYPE=REAL END
INDEx=    0    0    2 IOBS=    437675.00 SIGI=     25406.00
                      FOBS=     661.57 SIGMA=      19.49
INDEx=    0    0    4 IOBS=     19968.30 SIGI=       712.90
                      FOBS=     141.31 SIGMA=       2.55
INDEx=    0    0   10 IOBS=    112547.00 SIGI=      3318.00

I don't know where the problem lies. If anyone knows, can you please
suggest a possible
remedy?

Thanks very much,
Pradeep